Ruthenium Terpyridine Complexes Containing a Pyrrole-Tagged 2,2鈥?Dipyridylamine Ligand鈥擲ynthesis, Crystal Structure, and Electrochemistry

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• 作者：Kwong-Chak Cheung ; Peng Guo ; Ming-Him So ; Zhong-Yuan Zhou ; Lawrence Yoon Suk Lee ; Kwok-Yin Wong
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：June 18, 2012
• 年：2012
• 卷：51
• 期：12
• 页码：6468-6475
• 全文大小：444K
• 年卷期：v.51,no.12(June 18, 2012)
• ISSN：1520-510X

文摘

Ruthenium(II) terpyridine complexes containing the pyrrole-tagged 2,2鈥?dipyridylamine ligand PPP (where PPP stands for N-(3-bis(2-pyridyl)aminopropyl)pyrrole with the general formula [Ru(tpy)(PPP)X]ⁿ⁺ (1, X = Cl^{鈥?/sup>; 2, X = H₂O; 3, X = CH₃CN; tpy = 2,2鈥?6鈥?2鈥?terpyridine) have been synthesized and characterized by 1H NMR, IR, UV鈥搗is, mass spectrometry, and elemental analysis. 1 and 2 have been structurally characterized by X-ray crystallography. Both 1 and 2 were successfully immobilized onto glassy carbon electrode via anodic oxidation of the pyrrole moiety on the PPP ligand to give stable and highly electroactive polymer films. Cyclic voltammetric studies of 1 in acetonitrile revealed a RuIII/RuII couple at 0.4 V vs Cp₂Fe+/0 initially, but another redox couple resulting from chloride substitution by acetonitrile developed at E_1/2 = 0.82 V upon repetitive potential scan. This ligand substitution was induced by the acidic local environment caused by the release of protons during pyrrole polymerization. The electropolymerization of 2 in aqueous medium allowed the observation of the formation of RuIV鈺怬 species in polypyrrole film. As the film grew thicker, the size of the RuIII//RuII couple (E_1/2 = 0.8 V vs SCE at pH 1) of poly[Ru(tpy)(PPP)(OH₂)]n+ increased accordingly, whereas the growth of the RuIV/RuIII couple (E_1/2 = 0.89 V vs SCE at pH 1) leveled off after the film had reached a certain thickness. The Pourbaix diagram of the E_1/2 of the RuIII /RuII and RuIV/RuIII couples vs pH of the electrolyte medium has been obtained. The resulting poly[Ru(tpy)(PPP)(OH₂)]n+ film is electrocatalytically active toward the oxidation of benzyl alcohol.}